# Fenton Treatment of Filter Backwash Water for Recycling in DWTP

## TL;DR

This paper explores using Fenton treatment to recycle filter backwash water in drinking water treatment plants, effectively removing contaminants and microorganisms.

## Contribution

The study demonstrates the use of Fenton reactions with iron from filter backwash water to inactivate microorganisms and improve water quality for recycling.

## Key findings

- Bench-scale tests achieved 100% inactivation of Escherichia coli using Fenton treatment.
- The sedimentation stage achieved 99.1% turbidity removal and 99.9% color removal.
- pH and hydrogen peroxide concentration significantly influenced microorganism removal.

## Abstract

Drinking water treatment plants (DWTPs) generate residues, such as filter backwash water (FBW), that can harm the aquatic environments if discharged into water sources. In this sense, FBW recycling has gained attention. Nevertheless, it requires treatment to maintain operational efficiency and water quality in the DWTP. This work analyzed the main variables interfering with Fenton treatment of FBW from a full‐scale DWTP aiming at removing turbidity and microorganisms. Bench‐scale tests successfully inactivated 100% of
Escherichia coli
. Desired removal of other parameters (99.1% of turbidity, 99.9% of color, and achieving a 2.5 log10 reduction of aerobic endospores) occurred during the sedimentation stage. There was a strong influence of the pH sample and the concentration of added hydrogen peroxide on the removal of microorganisms. This study represents an initial stage that should be continued to enable the removal of resistant microorganisms through oxidation by the Fenton reaction in FBW treatment.

Treatment of filter backwash water (FBW) enables safe water recycling in DWTP.Fe from FBW was used to promote Fenton reactions, minimizing reagent costs.AOP/Fenton was shown to be a potential process to inactivate microorganisms in FBW.

Treatment of filter backwash water (FBW) enables safe water recycling in DWTP.

Fe from FBW was used to promote Fenton reactions, minimizing reagent costs.

AOP/Fenton was shown to be a potential process to inactivate microorganisms in FBW.

The graphical abstract illustrates the treatment and recycling pathway of filter backwash water (FBW) generated in drinking water treatment plants. The proposed treatment innovatively applies the Fenton advanced oxidation process, using the iron naturally present in the FBW, with a sedimentation step for effective clarification.